“Victoria and colleagues have identified the contamination of live viral vaccines for use in healthy children, with viral nucleic acids; the findings have since been confirmed by the vaccine manufacturers and the data reported to the FDA. Contaminating nucleic acids include retroviral sequences from the producer chicken and primate cells. Specifically, Avian leucosis virus (ALV) was present as RNA in viral particles while simian retrovirus (SRV) was present as genetically defective DNA. Rotarix, an orally administered rotavirus vaccine, contained nucleic acids from porcine circovirus-1 (PCV1), virus. Since this report, a second rotavirus vaccine (RotaTeq) has been shown to contain nucleic acids from both PCV1 and PCV2, a pathogen in pigs that is associated with wasting and immunodeficiency. The circumstances in which PCV2 induces disease are discussed below.“3.